Oil discharge assembly for a turbocharger

ABSTRACT

A turbocharger assembly ( 100 ) includes an insert ( 200 ) having an outer axially extending lip ( 204 ) and an inner axially extending lip ( 208 ). The outer lip ( 204 ) is radially spaced from the inner lip ( 208 ), and the inner lip ( 208 ) has a radially outwardly extending tip ( 212 ). The inner lip ( 208 ) can define an annular drainage channel ( 216 ). The insert ( 200 ) is positioned in the turbocharger assembly ( 100 ) so as to engage a thrust collar ( 124 ) and a thrust bearing ( 140 ). The insert ( 200 ), the thrust collar ( 124 ) and the thrust bearing ( 140 ) can cooperatively define an oil collection chamber ( 240 ). The oil collection chamber ( 240 ) is in fluid communication with an oil release interface defined between the thrust collar ( 124 ) and the thrust bearing ( 140 ). Pressurized oil discharged from the oil release interface is centrifugally propelled toward a radially outer region of the oil collection chamber ( 240 ) and can gravitationally collect in the drainage channel ( 216 ), which can direct the oil out of the turbocharger assembly ( 100 ).

FIELD OF THE INVENTION

The invention relates in general to turbochargers and, moreparticularly, to preventing oil leakage into the compressor of aturbocharger.

BACKGROUND OF THE INVENTION

Turbochargers can have a turbine wheel that is connected by a shaft to acompressor wheel. The turbine wheel is driven by exhaust gas exiting aninternal combustion engine. The rotation of the turbine wheel iscommunicated to the compressor wheel by the shaft. The compressor wheelis used to increase the pressure of intake air prior to mixing with fueland combustion in the engine. The speeds at which the shaft, turbinewheel and compressor wheel are rotated is very high, and can be inexcess of 250,000 rpm. Therefore, bearings used to support the shaftmust be lubricated with pressurized oil. During normal operation of theturbocharger, pressure within the compressor is sufficient to retard theflow of oil from the area of the bearings into the compressor. However,during certain operational states, pressure is reduced in the compressorand pressurized oil can be drawn into the compressor area where the oilwill contaminate the intake air.

This lubricant is ultimately emitted into the environment via theexhaust, contributing to emissions that may not be in compliance withthe increasingly stringent emissions standards that turbochargedvehicles are required to meet. Further, such emissions can potentiallyharm certain downstream components (i.e., catalytic converters).However, it is a challenge to prevent the flow of lubricant into thecompressor, considering that lubricating oil is pumped in underpressure, at a high flow rate, to lubricate and remove heat from aturbine shaft rotates at high speeds.

One example of such a system for containing the flow of lubricant intothe compressor is shown in FIG. 1. The system includes a turbocharger 10that has a turbine wheel 14, a compressor wheel 18, and a connectingshaft 22. A first journal bearing 26 and a second journal bearing 28 canbe provided to support the shaft 22. An oil intake 30 communicates withoil passages 34, 38 to deliver oil to the first journal bearing 26 andthe second journal bearing 28. Additionally, a thrust collar 40 is fixedto and rotates with the shaft 22. The thrust collar 40 includes a firstradially outwardly extending wall 44 and a second radially outwardlyextending wall 48 (FIG. 2). A thrust bearing 50 has a radially inner end54 that rests in an annular channel formed by the first radiallyoutwardly extending wall 44 and second radially outwardly extending wall48 of the thrust collar 40. The thrust bearing 50 controls axiallydirected movement of the shaft 22 as well as radial shaft vibration.

Lubrication is provided by oil passageway 60 which receives oil from theoil intake 30. Oil escaping from the interface between the firstradially outwardly extending wall 44 and the thrust bearing 50 isprevented from reaching the compressor wheel 18 by the provision of aseal assembly including an oil deflector 64 and an insert 68. Thedeflector 64 has an irregular form to facilitate the drainage of oil.Oil passing the deflector 64 is contacted by an oil thrower 72. The oilthrower 72 is connected to the shaft 22 and rotates therewith. Oil isthrown by the thrower 72 into the chamber 76 where it contacts adeflecting surface 80. The deflecting surface 80 collects the oil andthe oil flows gravitationally to the outlet 84.

However, this configuration is mechanically complicated because itintroduces an additional component (the oil deflector 64) to theassembly. Further, oil can become stuck between two surfaces due tosurface tension and capillary action, preventing the oil from drainingdue to gravity and potentially blocking the drainage of other oil. Anyoil trapped in the area increases the likelihood that it will be drawninto the compressor. Despite the tortuous path created by the presenceof the insert 68, the oil deflector 64 and the oil thrower 72, the oilcan nevertheless flow past the interstices between the insert 68 and theoil thrower 72 to reach the compressor wheel 18.

The prior art is replete with additional systems for preventinglubricant flow into the compressor. For instance, many references aredirected to systems with double ring seals. Some references usepressurized gas or venting to air in combination with the seals toprevent undesired migration of the lubricant. Examples of such systemsare disclosed in U.S. Pat. Nos. 3,825,311; 4,196,190; 5,076,765; and5,890,881 as well as in International Publication No. WO2004/063535 andEuropean Patent Specification No. EP0941431. However, these systems canbe overly complicated, unreliable, expensive to incorporate and thus notuniversally adopted, and liable to wear out. Thus, there is a need for aturbocharger assembly that can minimize such concerns.

SUMMARY OF THE INVENTION

A turbocharger assembly according to aspects of the invention includes athrust collar, a thrust bearing and an insert. The thrust collar has afirst radially outwardly extending wall and a second radially outwardlyextending wall. The first and second radially outwardly extending wallsare axially spaced such that an annular channel is defined therebetween.The first radially outwardly extending wall has a proximal face and adistal face. Likewise, the second radially outwardly extending wall hasa proximal face and a distal face. The annular channel is formed in partby the distal face of the first radially outwardly extending wall andthe proximal face of the second radially outwardly extending wall.

A thrust bearing has a first axial face and a second axial face. Thethrust bearing further has a radially outer end and a radially innerend. At least a portion of the thrust bearing including the radiallyinner end is received in the annular channel.

The insert has an outer axially extending lip and an inner axiallyextending lip. The outer lip is radially spaced from the inner lip. Theinner lip has a radially outwardly extending tip. The inner lip definesan annular drainage channel. The insert annularly surrounds a portion ofthe thrust collar such that the tip of the inner lip directly engagesthe proximal face of the first radially outwardly extending wall andsuch that the outer lip directly engages the first axial face of thethrust bearing proximate the radially outer end.

An oil collection chamber is defined at least in part by the drainagechannel of the insert, the first radially outwardly extending wall ofthe thrust collar and the first axial face of the thrust bearing. Thechamber is in fluid communication with an oil release interface definedbetween the first radially outwardly extending wall and the thrustbearing. Thus, pressurized oil discharged from the oil release interfaceis permitted to be centrifugally propelled toward a radially outerregion of the oil collection chamber and to collect in the oilcollection chamber for subsequent drainage.

The insert can include a deflecting surface. The deflecting surface canform a part of the oil collection chamber. The deflecting surface can beangular, or it can be substantially curvilinear.

The first radially outwardly extending wall can have an associateddiameter and the radially outwardly extending tip can have an associatedsecond diameter. In one embodiment, the second diameter can be greaterthan the first diameter. In another embodiment, the second diameter canbe less than the first diameter. In such case, the first radiallyoutwardly extending wall can be at a first diameter at the proximal faceand at a second diameter at the distal face. The first diameter can begreater than the second diameter such that a sharp edge is formed at theproximal face.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a prior art turbocharger.

FIG. 2 is an enlarged cross-sectional view of an oil deflector assemblyin the turbocharger of FIG. 1.

FIG. 3 is a cross-sectional view of a turbocharger with an oil dischargeassembly according to aspects of the invention.

FIG. 4 is a schematic diagram illustrating an oil discharge assemblyaccording to aspects of the invention.

FIG. 5A is a perspective view of an insert according to aspects of theinvention.

FIG. 5B is a perspective view, broken away partially in cross-section,of the insert of FIG. 5A.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention are directed to an oil discharge assemblyfor a turbocharger. Aspects of the invention will be explained inconnection with one possible oil discharge assembly, but the detaileddescription is intended only as exemplary. Embodiments of the inventionare shown in FIGS. 3-5B, but the present invention is not limited to theillustrated structure or application.

Referring to FIGS. 3-4, aspects of the invention relate to aturbocharger 100. The turbocharger 100 has a turbine housing 101, acompressor housing 102 and a center or bearing housing 103. Theturbocharger 100 can include a turbine wheel 104 and a compressor wheel108 that are connected by a shaft 112. The compressor wheel 108 can beprovided in a compressor assembly 110. The shaft 112 is supported by afirst journal bearing 116 and a second journal bearing 120.

The turbocharger 100 can further include a thrust collar 124. The thrustcollar 124 can be generally cylindrical with a first radially outwardlyextending wall 130 and a second radially outwardly extending wall 134.The first radially outwardly extending wall 130 has a proximal face 131and a distal face 133. The second radially outwardly extending wall 134has an proximal face 135 and a distal face 137. It should be noted thatthe terms “proximal” and “distal,” as used herein, are intended to meanrelative to the compressor assembly 110. The first and second radiallyoutwardly extending walls 130, 134 are axially spaced such that anannular channel 160 is formed therebetween. The annular channel 160 canbe defined in part by the distal face 133 of the first radiallyoutwardly extending wall 130 and the proximal face 135 of the secondradially outwardly extending wall 134.

The assembly further includes a thrust bearing 140. The thrust bearing140 has a first axial face 144 and a second axial face 148. The thrustbearing 140 has a radially outer end 152 and a radially inner end 156.At least a portion of the thrust bearing 140, including the radiallyinner end 156, is received in the annular channel 160.

Pressurized oil is provided through an oil intake 170 and through apassageway 174 to the thrust bearing 140. Oil is transported through apassageway 178 to the first journal bearing 116 and through a passageway182 to the second journal bearing 120. Oil making its way toward thecompressor 110 is blocked by an insert 200. The insert 200 is generallyannular and has an outer axially extending lip 204 and an inner axiallyextending lip 208. The inner lip 208 has a radially outwardly extendingtip 212 such that the inner lip 208 defines an annular drainage channel216. The insert 200 can be made of any suitable material, such as iron.

The insert 200 annularly surrounds the thrust collar 124. A portion ofthe outer lip 204 of the insert 200 can directly engage the housing 102.A portion of outer lip 204 can directly engage the first face 144 of thethrust bearing 140 proximate the radially outer end 152. The inner lip208 of the insert 200 can directly engage the thrust collar 124. The tip212 of the inner lip 208 can directly engage the proximal face 131 ofthe first radially outwardly extending wall 130 of the thrust collar124. In one embodiment, the diameter of the outwardly extending tip 212can be greater than the diameter of the first radially outwardlyextending wall 130 of the thrust collar 124, as shown in FIG. 3.Alternatively, the diameter of the outwardly extending tip 212 can beless than the diameter of the first radially outwardly extending wall130 of the thrust collar 124. In such case, the first radially outwardlyextending wall 130 can be angled relative to the centerline of the shaft112 or otherwise to horizontal so as to form a sharp edge. FIG. 4 showsan embodiment in which a sharp edge 138 is formed when the diameter ofthe first radially outwardly extending wall 130 can be greater at theproximal face 131 than the distal face 133.

An oil collection chamber 240 is defined at least in part by thedrainage channel 216 of the insert 200, the first radially outwardlyextending wall 130 of the thrust collar 128 and the first axial face 144of the thrust bearing 140. The chamber is in fluid communication with anoil release interface between the distal face 133 of the first radiallyoutwardly extending wall 130 and the first axial face 144 of the thrustbearing 140.

Oil discharged from the oil release interface is centrifugally propelledfrom the interface as generally indicated by arrow 250. In cases wherethe first radially outwardly extending wall 130 provides a sharp edge138, as described above, the oil can be broken apart by the edge 138 asit is propelled outward. The oil can be propelled toward a radiallyouter region of the oil collection chamber 240 as indicated by arrow251. The oil can strike a deflecting surface 206 of the insert 200 andcan follow the path of arrows 252-255 to the drainage channel 216. Thedeflecting surface 206 can be contoured to generally direct the oildownward. In one embodiment, the deflecting surface 206 can besubstantially curvilinear or otherwise smooth, as shown in FIG. 3.Alternatively, the deflecting surface 216 can be angular, as shown inFIG. 4. In such case, the deflecting surface 206 can include an upperdeflecting surface 205, a downwardly angled surface 207, a proximal wall209 that can be substantially vertical, a base 211, and a distal wall213 (which is an outer surface of the tip 212). Oil collected in thedrainage channel 216 can flow gravitationally to an outlet 270, wherethe oil can be returned to a sump or reservoir or otherwise exits theturbocharger assembly 100.

According to aspects of the invention, it is preferred for the oilcollection chamber 240 to be as large as possible. The larger thechamber 240, the more difficult it is for oil to stick between twosurfaces of the chamber 240. Thus, the likelihood that the oil willdrain out of the oil collection chamber 240 can be increased.

There is shown in FIG. 5 an insert 200 in accordance with aspects of theinvention. The insert 200 can include a first radially outwardlyextending wall 203 and a second radially outwardly extending wall 205.The walls 203 and 205 form a groove 209 capable of receiving sealingstructure, such as an o-ring seal 215 (FIG. 3), for sealing to housing102. Similarly, sealing structure, such as o-ring seals 217 and 219, canbe provided to seal the thrust collar 124 to the insert 200 (FIG. 3).

The foregoing description is provided in the context of one possible oildischarge assembly for a turbocharger. Thus, it will of course beunderstood that the invention is not limited to the specific detailsdescribed herein, which are given by way of example only, and thatvarious modifications and alterations are possible within the scope ofthe invention as defined in the following claims.

1. A turbocharger assembly comprising: a thrust collar (124) having afirst radially outwardly extending wall (130) and a second radiallyoutwardly extending wall (134), the first and second radially outwardlyextending walls (130, 134) being axially spaced such that an annularchannel (160) is defined therebetween, the first radially outwardlyextending wall (130) having a proximal face (131) and a distal face(133), the second radially outwardly extending wall (134) having aproximal face (135) and a distal face (137), wherein the annular channel(160) is formed in part by the distal face (133) of the first radiallyoutwardly extending wall (130) and the proximal face (135) of the secondradially outwardly extending wall (134); a thrust bearing (140) having afirst axial face (144) and a second axial face (148), the thrust bearing(140) further having a radially outer end (152) and a radially inner end(156), at least a portion of the thrust bearing (140) including theradially inner end (156) being received in the annular channel (160);and an insert (200) having an outer axially extending lip (204) and aninner axially extending lip (208), the outer lip (204) being radiallyspaced from the inner lip (208), the inner lip (208) having a radiallyoutwardly extending tip (212), wherein the inner lip (208) defines anannular drainage channel (216), the insert (200) annularly surrounding aportion of the thrust collar (124) such that the tip (212) of the innerlip (208) directly engages the proximal face (131) of the first radiallyoutwardly extending wall (130) and such that the outer lip (204)directly engages the first axial face (144) of the thrust bearing (140)proximate the radially outer end (152), wherein an oil collectionchamber (240) is defined at least in part by the drainage channel (216)of the insert (200), the first radially outwardly extending wall (130)of the thrust collar (124) and the first axial face (144) of the thrustbearing (140), the chamber (240) being in fluid communication with anoil release interface between the first radially outwardly extendingwall (130) and the thrust bearing (140), whereby pressurized oildischarged from the oil release interface is permitted to becentrifugally propelled toward a radially outer region of the oilcollection chamber (240) and to collect in the oil collection chamber(240) for subsequent drainage.
 2. The turbocharger assembly of claim 1wherein the insert (200) includes a deflecting surface (206), whereinthe deflecting surface (206) forms a part of the oil collection chamber(240), wherein the deflecting surface (206) is angular.
 3. Theturbocharger assembly of claim 1 wherein the insert (200) includes adeflecting surface (206), wherein the deflecting surface (206) forms apart of the oil collection chamber (240), wherein the deflecting surface(206) is substantially curvilinear.
 4. The turbocharger assembly ofclaim 1 wherein the first radially outwardly extending wall (130) has anassociated diameter and the radially outwardly extending tip (212) hasan associated second diameter, wherein the second diameter is greaterthan the first diameter.
 5. The turbocharger assembly of claim 1 whereinthe first radially outwardly extending wall (130) has an associateddiameter and the radially outwardly extending tip (212) has anassociated second diameter, wherein the second diameter is less than thefirst diameter.
 6. The turbocharger assembly of claim 5 wherein thefirst radially outwardly extending wall (130) is at a first diameter atthe proximal face (131) and at a second diameter at the distal face(133), wherein the first diameter is greater than the second diameter,whereby a sharp edge (138) is formed at the proximal face (131).